16 Mr. Davy’s Experiments on the 
ought to absorb nearly 2 cubical inches of oxymuriaticgas, and 
that the same quantity converted into soda, would decompose 
nearly four cubical inches of muriatic gas. Muriate of soda 
ought on this idea to contain one proportion of sodium, 22., 
and one of oxymuriatic gas 32.9; and this estimation is very 
near that which may be gained from Dr. Marcet’s analysis 
of this substance. Hydrat of potash ought to consist of 
1 proportion of potash, represented by 48., and one of water, 
represented by 8.5. This gives its composition as 15.1 of 
water, and 84.9 of potash. Hydrat of soda ought, according to 
theory, to contain 1 proportion of soda 29.5, and 1 of water 
3.5, which will give in 100 parts 22.4 of water; and the 
experiments that I have detailed, conform as well as can be 
expected with these conclusions. 
The proportions of potash and soda indicated, in different 
•neutral combinations, by these estimations, will be found to 
agree very nearly with those derived from the most accurate 
analysis, particularly those of M. Berthollet ; or the dif- 
ferences are such as admit of an easy explanation. 
I stated in my last communication, the probability that the 
oxygene in the hyperoxymuriate of potash was in triple com- 
bination with the metal and oxymuriatic gas ; the new facts 
that water consists of i particle of oxygene, and i of hydrogene ; but I have since 
found that this opinion is advanced, in a work published in 1789. A comparative 
View of the Phlogistic and Antiphlogistic Theories, by Willia m Hi gg in*. In 
this elaborate and ingenious performance, Mr. Higgins has developed many happy 
sketches of the manner in which (on the corpuscular hypothesis) the particles or 
molecules of bodies may be conceived to combine ; and some of his views, though 
formed at this early period of investigation, appear to me to be more defensible, as- 
suming his data, than any which have been since advanced; for instance, he considered 
nitrous gas as composed of two particles of oxygene, and one of nitrogene.- Mr. 
Higgins had likewise drawn the just conclusion respecting the constitution of 
